1. Field of the Invention
Embodiments of the present invention generally relate to the fabrication of integrated circuits. More particularly, embodiments of the present invention relate to a method for depositing organosilicate layers on a substrate.
2. Description of the Related Art
In the manufacture of integrated circuits, plasma processes are increasingly being used to replace thermal processes. Plasma processing provides several advantages over thermal processing. For example, plasma enhanced chemical vapor deposition (PECVD) allows deposition processes to be performed at substantially lower temperatures than the temperatures required in analogous thermal processes. This is advantageous for processes with stringent thermal budget demands, such as in very large scale or ultra-large scale integrated circuit (VLSI or ULSI) device fabrication.
In order to further reduce the size of devices on integrated circuits, it has become necessary to use conductive materials having low resistivity and to use insulators having low dielectric constants (low-k) to reduce the capacitive coupling between adjacent metal lines. Methods to form low-k dielectric layers include PECVD of organosilicate precursor gases to form organosilicate dielectric layers, such as carbon doped silicon oxide films. One challenge in this area has been to develop a carbon doped silicon oxide dielectric film that has a low k value, but also exhibits desirable adhesion properties to the underlying substrate or adjacent dielectric diffusion barrier layer materials which include silicon, silicon dioxide, silicon carbide, silicon nitride, oxygen-doped silicon carbide, titanium, titanium nitride, tantalum, tantalum nitride, tungsten, aluminum, copper, and combinations thereof. Inadequate adhesion may result in delamination of the low-k dielectric layer from the underlying substrate and potential failure of the device. One approach to enhancing adhesion of carbon doped silicon oxide films is inserting a thin silicon oxide film and a thin transition film between the carbon doped silicon oxide layer and the underlying barrier layer. However, the thin silicon oxide and transition layers must be a minor portion of the combined dielectric film to retain significant reduction in dielectric constant. Therefore there is a need for a process for making low dielectric constant materials with a controlled silicon oxide layer and transition layer.